JP3052678B2 - Active suspension - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active suspension and, more particularly, to an active suspension capable of reducing an uncomfortable feeling felt by an occupant when a roll of a vehicle body generated during a turn is restored.

[0002]

2. Description of the Related Art A hydraulic cylinder and a spring interposed between a vehicle body and each wheel as an active suspension for controlling a vehicle body roll during a turn, and a working fluid pressure of the hydraulic cylinder according to a command value. Pressure control valve, a lateral acceleration detecting or estimating means for obtaining the lateral acceleration of the vehicle body, and a control device for outputting a command value according to the detected value or the estimated value of the lateral acceleration detecting or estimating means. There is something.

[0003] In such an active suspension, the lateral acceleration y "(positive value when turning right) is plotted on the horizontal axis.
Working pressure p of the fluid cylinder (that is, output pressure of the pressure control valve)
FIG. 22 shows an example of the control characteristic in which is plotted on the vertical axis. In this figure, the horizontal axis corresponds to p = P _N (neutral pressure). In other words, when the lateral acceleration y ″ = 0 when traveling straight ahead, the operating pressures p of the left and right wheels are both at the predetermined neutral pressure _PN , and the absolute value of the lateral acceleration | y ″ | is the predetermined value a _c
When the operating pressure p is equal to or less than P ₀ (= the maximum control pressure P _MAX −P _N ) or the absolute value of the lateral acceleration when −P ₀ ), the lateral acceleration | y ″ | Accordingly, the operating pressures P on the turning outer wheel side and the inner wheel side both have the same rate of change, the turning outer wheel side increases, the turning inner wheel side decreases, and changes symmetrically between right turning and left turning. the absolute value of the lateral acceleration | y "| when is less than a predetermined value a _c, does not cause the roll to the vehicle body, are so-called Roruzero control is performed.

However, in such control characteristics,
The absolute value of the lateral acceleration | y "| exceeds a predetermined value a _c (for example, in FIG. 22 | y" | = a a) and the working pressure p is P
_Since it is held at ₀ or −P ₀ , a roll is generated in the vehicle body, and the spring inserted between the vehicle body and each wheel contracts on the turning outer wheel side and deforms in a direction extending on the inner wheel side. At that time, the energy corresponding to the amount of deformation [for example, 0 ≦
| Y "| ≦ a output linearity of extension and the straight line of each wheel in the _c | y" | a = pressure indicated by the intersection between a (eg P _A), P
Energy E _a ] corresponding to the difference from ₀ is accumulated.

In this state, the absolute value of the lateral acceleration | y ″ | decreases with the convergence of the turn, and when the rolled vehicle body returns to its original state, the absolute value of the lateral acceleration | At the time when y ″ | changes from a to _ac , the energy (for example, E _a ) stored on the outer ring side is released.

[0006]

However, if the roll is returned in such a short time that the absolute value | y ″ | of the lateral acceleration changes from a to _ac in such a short time, the occupant will feel uncomfortable when the vehicle body returns to its original state. The present invention has been made in view of such a problem of the related art, and by making the roll return gradual, when the rolled vehicle body returns during a turn, An object is to reduce discomfort felt by an occupant.

[0007]

In order to achieve the above object, a first aspect of the present invention is directed to a fluid cylinder interposed between a vehicle body-side member and a wheel-side member for each wheel, as shown in FIG. A spring, a control valve for individually controlling each of the fluid cylinders according to a command value, a lateral acceleration detecting or estimating means for detecting or estimating the lateral acceleration of the vehicle body, and a lateral acceleration of the lateral acceleration detecting or estimating means. Command value calculating means for calculating, for each wheel, a command value given to each control valve based on a detected or estimated value; command value output means for outputting the command value calculated by the command value calculating means to the control valve; Wherein the command value calculation means has spring deformation correction means for correcting the amount of deformation of the spring by the roll with respect to the command value when the vehicle body rolls back. To provide a scan pension.

A second aspect of the present invention is an active type wherein the spring deformation correcting means in the first aspect emits energy stored in the outer ring side spring when the vehicle body rolls and supplies energy to the inner ring side spring. Provide suspension.
According to a third aspect of the present invention, there is provided an active suspension, wherein the spring deformation correcting means according to the first or second aspect corrects the deformation of the spring according to the lateral acceleration detected or estimated by the lateral acceleration detecting or estimating means. I do.

According to a fourth aspect of the present invention, there is provided an active suspension according to the first or second aspect, wherein the spring deformation correcting means includes a stroke detecting means, and corrects a deformation of the spring according to a value detected by the stroke detecting means. I will provide a.

[0010]

In the active suspension according to the first aspect, when the vehicle body rolls back, the amount of deformation of the spring due to the roll is corrected by the spring deformation correcting means. Therefore, the spring deformation correcting means is stored in the spring on the outer ring side during turning. If the roll returns, the energy stored in the spring on the turning outer wheel is released or the energy is supplied to the spring on the turning inner wheel when the roll returns. The command value corrected in such a manner is calculated for each wheel by the command value calculating means. Each command value is output to the control valve by the command value output means. Here, for example, when a pressure control valve is used as the control valve,
Thereby, when the roll returns, the operating pressure of the fluid cylinder on the turning outer wheel side becomes lower than normal, or the operating pressure of the fluid cylinder on the turning inner wheel side becomes higher than normal. According to this control, the operating pressure of each fluid cylinder is corrected in a direction that promotes the roll of the vehicle body, and as a result, the roll returns slowly. At this time, as in the active suspension according to claim 2, when the correction is performed, the energy stored in the spring on the turning outer wheel side is released at the same time as the energy is supplied to the spring on the turning inner wheel side. The vehicle body can be returned without changing the center.

In correcting the energy of the turning outer wheel and the energy of the inner wheel as described above, in the active suspension according to the third aspect, for example, the rate of decrease of the control pressure of the outer wheel and the rate of increase of the inner wheel with respect to the decrease of the lateral acceleration accompanying the turning convergence are determined. By performing the correction, the time until the roll returns can be controlled to suppress a sudden change in the transient characteristic. On the other hand, in the active suspension according to the fourth aspect, if the suspension stroke is detected and changed in a direction in which the stroke change rate is suppressed at the time of roll return, the suspension is returned to the opposite direction which occurs at the time of return such as causing backlash. Roll speed can be reduced, and rapid changes in vehicle body behavior due to roll convergence are suppressed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The active suspension of each embodiment shows a case where only the roll control of the vehicle body is performed. First, a first embodiment of the present invention will be described with reference to FIGS. In FIG. 2, 1
0 is the vehicle body side member which is a suspension arm, 11FL
11RR indicates front left to rear right wheels, and 12 indicates an active suspension.

The active suspension 12 includes a hydraulic cylinder 18 as a fluid cylinder interposed between the vehicle body-side member 10 and each wheel-side member 14 of the wheels 11FL to 11RR.
FL-18RR, pressure control valves 20FL-20RR for individually adjusting the operating pressures of the hydraulic cylinders 18FL-18RR, a hydraulic source 22 of the hydraulic system, and a hydraulic pressure between the hydraulic source 22 and the pressure control valves 20FL-20RR. Accumulators 24 and 24 for accumulating pressure inserted by pipes 22a and 22b, and a lateral acceleration sensor 26 for detecting acceleration generated in the lateral direction of the vehicle body
And a controller 30 for individually controlling the output pressures of the pressure control valves 20FL to 20RR based on the detection signal of the lateral acceleration sensor 26. Also, hydraulic cylinder 18FL ~
Each of the pressure chambers L of the 18RR described later is connected to an accumulator 34 for absorbing unsprung vibration via a throttle valve 32. Further, a coil spring 36 having a relatively low spring constant and supporting a static load of the vehicle body is provided between the upper and lower portions of each of the hydraulic cylinders 18FL to 18RR.

Each of the hydraulic cylinders 18FL to 18RR has a cylinder tube 18a.
In a, a lower pressure chamber L separated by a piston 18c is formed. Then, the cylinder tube 18a
Is attached to the wheel-side member 14, and the upper end of the piston rod 18 b is attached to the vehicle-side member 10. Each of the pressure chambers L is connected to an output port of each of the pressure control valves 20FL to 20RR via a hydraulic pipe 38.

Each of the pressure control valves 20FL to 20RR has a well-known three-port proportional electromagnetic pressure reducing valve (for example, disclosed in 64-74111). Then, by adjusting the command current i (command value) supplied to the exciting coil of the proportional solenoid,
The operation of controlling the moving distance of the poppet accommodated in the valve housing, that is, the position of the spool, and allowing the poppet to flow between the hydraulic source 22 and the hydraulic cylinders 18FL to 18RR via the supply port and the output port or the output port and the return port. The oil can be controlled.

FIG. 3 shows the relationship between the command current i (: i _{FL to} i _RR ) applied to the exciting coil and the control pressure p output from the output port of the pressure control valve 20FL (to 20 _RR ). As shown. In other words, when the current value is the minimum current value i _MIN in consideration of the noise, the control pressure P _NIM is at the minimum. When the current value i is increased from this state, the control pressure p increases linearly in proportion to the current value i, is the highest control pressure P _MAX corresponding to the set line pressure when the value i _MAX.
i _N is a neutral command current, and _PN is a neutral control pressure.

On the other hand, a lateral acceleration sensor 26 is fixed to the vehicle body. The lateral acceleration sensor 26 detects lateral (vehicle width) acceleration acting on the vehicle body. For example, the lateral acceleration sensor 26 outputs a voltage signal g corresponding to a displacement amount when a magnetically suspended mass is displaced by inertial force. Output to 30. As shown in FIG. 4, when the lateral acceleration y ″ = 0, the detection signal g = g _N (predetermined neutral lateral G
(Detection value), and increases or decreases in proportion to the lateral acceleration y ″ when the state shifts to the left turn or the right turn.
Here, the lateral acceleration y ″ is a positive value when turning right and a negative value when turning left.

Further, as shown in FIG. 5, the controller 30 includes an A / D converter 70 for converting a detection signal g according to the input lateral acceleration y ″ into a digital quantity, as shown in FIG.
A microcomputer 72 for arithmetic processing _; D / A converters 73A to 73D for individually converting digital voltage command values V _{FL to} V _RR output from the microcomputer 72 into analog quantities; Voltage command value V
Drive circuits 74A to 74D are provided to make the command currents i _{FL to} i _RR individually output to the pressure control valves 20FL to 20 _RR follow the target values with _{FL to} V _RR as target values.

The microcomputer 72 includes at least an interface circuit 76 and an arithmetic processing unit 78.
And a storage device 80 such as a RAM and a ROM, and the interface circuit 76 includes an I / O port and the like. Further, the arithmetic processing unit 78 reads the detection signal g via the interface circuit 76, and performs an arithmetic operation and other processes described later based on the detection signal g. The storage device 80 stores in advance a predetermined program, fixed data, and the like necessary for execution of the processing of the arithmetic processing device 78, and also stores the processing results of the arithmetic processing device 78.

The microcomputer 72 includes:
The programs shown in FIGS. 6 and 7 are stored. Although the coefficient K _G that will be described later in this program is of the same absolute value set positive in the left wheel, a negative right wheel. In the program of FIG. 6, the detection signal g of the lateral acceleration sensor 26 is read in step S1, and the process proceeds to step S2. In step S2, by subtracting the neutral lateral G detected value g _N from the detection signal g read in step S1, determine the lateral acceleration detection signal Delta] g. Next, the process proceeds to step S3, and the lateral acceleration y ″ corresponding to the detection signal Δg is referred to by referring to a storage table stored in the storage device 80 in advance.
Is calculated.

Then, the process proceeds to step S4, in which the pressure command values P _{FL to} P _RR of each wheel are set according to a subroutine shown in FIG. The flag F1 in this program is F1 =
When 1, the lateral acceleration is decreasing during the turning convergence and the operating pressure correction control is being performed. When F1 = 0, the lateral acceleration is increasing due to the turning and the operating pressure correction is performed. Means not going. Also, P ₀ = best control pressure P _MAX - a neutral pressure P _N.

That is, in step S41, the previous and current lateral accelerations y ″ _(n−1) and y ″ _(n) are read, and the flow advances to step S42. Here, the previous lateral acceleration y ″
_(n-1) is compared with the current lateral acceleration y ″ _(n) to determine whether the lateral acceleration is increasing or decreasing. Then, the lateral acceleration is increased (ie, | y ″). _(n) | − | y ″
_{If (n−1)} | ≧ 0), the process shifts to step S43 to set the flag F1 to 0. Then, the process shifts to step S44 to calculate the pressure command value P = K _G · y ″ _(n) , and shifts to step S45.

[0023] In step S45, the absolute value of the pressure command value | P |, it is determined whether a P ₀ or less, | P |
≦ If P ₀ and goes to step S46 to set the P pressure command value, and further proceeds to step S47 and outputs the P as a pressure command value. In step S45, | P
If it is determined that |> P ₀ , the flow shifts to step S48 to set P ₀ to the pressure command value, and further shifts to step S47 to output P ₀ as the pressure command value P.

In step S42, the direction in which the lateral acceleration decreases
(That is, | y ″_(n)|-| Y ″ _(n-1)| <0)
If it is determined that it is determined that the
Judge whether lag F1 = 1 and if F1 ≠ 1,
Moves to step S50, and the previous pressure command value P_(n-1)
Is read, and the process proceeds to step S51 to set P_(n-1)/ Y "
_(n-1)To K_GM(Gain) and calculate this as the storage device
Then, the process proceeds to step S52. here
The flag F1 is set to 1, and the process proceeds to step S53 to press the pressure finger.
Price P = K_GM・ Y ″_(n)Is calculated, and then step S4
Then, the process goes to 7 to output this P as a pressure command value.

If it is determined in step S49 that the flag F1 = 1, the process proceeds to step S54, where the storage device 80
Load the K _GM stored, calculates the pressure command value _{P = K GM · y "(} n) and proceeds to step S53 from the,
The process shifts to step S47 to output this P as a pressure command value. After outputting the pressure command value in step S47, the process returns to the main program of FIG.

After that, the processing unit 78 proceeds to step S5 in FIG. 6 and executes the voltage command values V _FL -V _RR (set in step S4) to achieve the pressure command values P _FL -P _RR of each wheel. (The value corresponding to the actual operating pressure p obtained by adding the neutral pressure _PN to the pressure command values P _{FL to} P _RR ). Then, the process shifts to step S6 to individually output the voltage command values V _{FL to} V _RR to the D / A converters 73A to 73D via the interface circuit 76.

Next, the operation of the above embodiment will be described. Here, only the control performed depending on whether the vehicle body is going straight or turning and the vehicle body behavior are considered. When the ignition switch of the vehicle body is turned on, the controller 30 is activated, and executes a timer interrupt process shown in FIG. 6 every predetermined time (for example, 20 msec) during execution of a predetermined main program.

Now, it is assumed that the vehicle body is traveling straight at a constant speed on a flat road with no unevenness. Since no lateral acceleration caused by the pivoting in this state, the detection signal g of the lateral acceleration sensor 26 is its neutral value g _N, the controller 30
The lateral acceleration y ″ calculated by the above becomes zero (see steps S1 to S3 in FIG. 6). Also, | y ″ _(n) | − | y ″
_{Since (n-1)} | = 0, each of the pressure command values P _{FL to} P _RR = 0
(Operating pressure p = P _N ) (steps S41 to S4 in FIG. 7).
7). Therefore, voltage command values V _{FL to} V _RR = V
_N (the operating pressure p of the hydraulic cylinders 18FL~18RR voltage value for the P _N) is calculated (see step S5 in FIG. 6), the neutral voltage command value V _N is D / A converter 73A~
73D.

Then, voltage command values V _FL -V _RR (=) converted into analog quantities by D / A converters 73A-73D.
V _N ) is output as a target value to the drive circuits 74A to 74D, respectively, and the drive circuit 74A to 74D outputs the target value V _N.
The neutral command current i _N corresponding to the pressure control valves 20FL-20R
Supplied to R respectively. Thereby, the pressure control valve 20FL ~
The 20RR controls the operating pressures p of the hydraulic cylinders 18FL to 18RR to the neutral pressures _PN (see FIG. 3), so that each of the hydraulic cylinders 18FL to 18RR generates a force corresponding to the neutral pressure _PN , Is maintained in a neutral posture of the predetermined vehicle height value.

When the vehicle shifts from the straight traveling state at a constant speed to, for example, a right turning state, an inertial force acts on the right side of the vehicle body, and the left side of the vehicle body sinks and the right side tries to generate a roll that rises. At the time of this right turn, the detection signal g of the lateral acceleration sensor 26 is larger than the neutral lateral G detection value g _N by an amount corresponding to the turning speed and the like, so that the controller 30 has a lateral acceleration signal Δg> 0, In step S3 of FIG.
The positive lateral acceleration y ″ corresponding to g is calculated, and the pressure command values P _{FL to} P _{RR of} each wheel are set based on the lateral acceleration y ″.

Here, the pressure command value P on the left wheel side as the turning outer wheel will be described with reference to FIG. 8. When the lateral acceleration y ″ is increasing from step S41 to S42 and S43, the predetermined value a _c (P ₀ = K _G · a _c , maximum control pressure P
_{When MAX} = P ₀ + P _N ) or less, the pressure command value P increases along a straight line L ₁ calculated in step S44 and represented by P = K _G · y ″ set in steps S45 to S46. is controlled in. Thus, the hydraulic cylinder 18FL of the left wheel side, the working pressure p in 18RL and higher by the pressure command value P min from the neutral pressure P _N, the roll does not occur in the vehicle body. Thus the straight line L ₁ is Roruzero It is a control curve.

The lateral acceleration y ″ is determined in steps S41 to S4.
2, the predetermined value a_cBigger
If not, go from step S45 to S48 and go to S48.
And P ₀→ P, and the left outer wheel is activated.
Pressure p is P_MAXFurther increase in lateral acceleration
A roll is generated on the vehicle body with the
(For example, when y ″ = a, E_a)
Is accumulated.

If the lateral acceleration y "decreases from this state through steps S41 to S42 and S49, the previous lateral acceleration y" is reduced in steps S50 and S51.
_(n-1) and the pressure command value P _(n-1) , P _(n-1) / y "
_(n-1) is calculated as K _GM (gain), and the following step S
Straight L ₃ which is proportional to the lateral acceleration y "in each S53 through 49 from S50~52 or S54 (passing through the origin, the slope K
A straight line of _GM , which is on the lower pressure side than the straight lines L ₁ and L ₂ (P = P ₀ ). ), The pressure command value P is controlled so as to decrease along with the operating pressure p of the hydraulic cylinders 18FL and 18RL on the left wheel side.
Is controlled to a lower pressure than when the lateral acceleration is increased.

[0034] Accordingly, while the energy E _a that is accumulated in the interposed a spring between the vehicle body and the left wheel is released while the y "is from 0 to a, slowly roll back. Also, the inner ring The right wheel side pressure command value P is, as described above, the predetermined value a _c
The case below, is controlled. Thus, as decreases along the straight line L ₁₁ that pressure command value is expressed as P = K _G · y ", of the right wheel side hydraulic cylinder 18FR, the operating pressure p of the 18RR and as low as the pressure command value P min from the neutral pressure P _N, but does not cause the roll to the vehicle body, the roll is generated in the vehicle body lateral acceleration y "is in the increasing state when larger than a predetermined value a _c.

Then, the lateral acceleration y ″ decreases from this state.
If so, the previous lateral acceleration y ″ _(n-1)And pressure command value
P_(n-1)And from P_(n-1)/ Y "_(n-1)To K_GM(gain)
And a straight line L proportional to the lateral acceleration y ″₃₁(origin
Through the slope K_GMThe straight line L₁₁, L_{twenty one}(P = -P
₀) On the higher pressure side. Pressure to increase along)
The command value P is controlled, and the right wheel hydraulic cylinder 18FR, 1
The operating pressure p of 8RR is a higher pressure than when the lateral acceleration is increasing.
Controlled by force. As a result, the interposition between the vehicle body and the right wheel
While the energy is supplied to the spring
Returns.

As described above, when the roll returns, the energy stored in the outer ring-side spring is released in accordance with the decrease in the lateral acceleration, and the energy is supplied to the inner ring-side spring in accordance with the decrease in the lateral acceleration. Since the pressure command value is corrected, the roll returns slowly over a longer time than in the conventional case where the roll is returned while y ″ changes from a to _ac, and the vehicle body is returned without changing the roll center. Therefore, a sudden change in the vehicle body behavior at the time of roll return can be suppressed, and the uncomfortable feeling given to the occupant can be reduced as compared with the related art.

In this embodiment, the lateral acceleration sensor 2
6, A / D converter 70, and steps S1 to S in FIG.
3 constitutes the lateral acceleration detecting means, and corresponds to the step shown in FIG.
Steps S4 to S5 correspond to the command value calculating means, and correspond to Step S5 in FIG.
6, D / A converters 73A to 73D, drive circuit 74A
74D constitute command value output means. Also this
In the program, steps S49 to S54 correspond to the present invention.
It corresponds to a spring deformation correcting means. Here, the lateral acceleration y ″ is
In the decreasing state, the lateral acceleration y ″ is a _cIf
Is also determined by steps S49 to S54._GMIs calculated,
At this time, K_GM= K_GAnd the straight line L₁Or L₁₁Along
The pressure command value P is controlled as described above. That is, in this case
Steps S49 to S54 are performed by the spring deformation correcting means of the present invention.
Not applicable, but in this case the energy
(For example, when y ″ = a, E_a) Is not generated
You don't have to.

Next, a second embodiment of the present invention will be described. In this embodiment, a program shown in FIG. 9 is stored in the microcomputer 72 as a subroutine of step S4 in FIG. 6 instead of the program in FIG. 7 in the first embodiment. It has the same configuration as the example. Although the coefficient K _G that will be described later in this program is of the same absolute value set positive in the left wheel, a negative right wheel.

That is, in step S4 of FIG. 6, the following processing is performed based on FIG. The flag F1 in this program means that when F1 = 1, the lateral acceleration is decreasing during the turning convergence and the operating pressure correction control is being performed, and when F1 = 0, the lateral acceleration increases due to turning. Mean that the operating pressure correction has not been performed. Also, P ₀ = best control pressure P _MAX - a neutral pressure P _N, b is a predetermined lateral acceleration threshold that satisfies _{0 <b <a c, P} 1 satisfies P ₁ = K _G · b It is a pressure value.

In step S401, the previous and current horizontal
Speed y ″_(n-1), Y ″_(n)And pressure value P₀And read
Move to step S402. Where the previous lateral acceleration
y ″ _(n-1)And the current lateral acceleration y ″_(n)Compare with
It is determined whether the acceleration is increasing or decreasing. Soshi
And the direction in which the lateral acceleration increases (that is, | y ″)._(n)|-
| Y ″_(n-1)If | ≧ 0), the process proceeds to step S403.
And set the flag F1 to 0, and then proceed to step S404.
And the pressure command value P = K_G・ Y ″_(n)And calculate
The process moves to step S405.

[0041] In step S405, the absolute value of the pressure command value | P |, it is determined whether a P ₀ or less, | P
| Proceeds to ≦ P ₀ is long if the step S406 to set the P pressure command value, and further proceeds to step S407 and outputs the P as a pressure command value. Step S40
5 | P |> If it is determined that P ₀ Step S40
The P ₀ is set to the pressure command value shifts to 8, further proceeds to step S407 and outputs the P ₀ as the pressure command value P.

If it is determined in step S402 that the lateral acceleration is in the decreasing direction (that is, | y " _(n) |-| y" _(n-1) | <0), the flow proceeds to step S409. to read a stored in the storage device 80 with a predetermined lateral acceleration threshold b and a pressure value P _1, the process proceeds to step S410. In step S410, the absolute value of the lateral acceleration | y ″
Is smaller than or equal to b, and if | y ″ | ≦ b, the process proceeds to step S404 to execute steps S404 to S4.
Execute 07.

If it is determined in step S410 that | y ″ |> b, the flow shifts to step S411, where the flag F1 is set.
= What determines whether a 1 reads the last pressure instruction value P _(n-1) proceeds to step S412 in the case of F1 ≠ 1, the process proceeds to step S413 (P ₀ -P ₁₎ /
(Y ″ _(n−1) −b) as K _GM (gain) and P ₀ −
[(P ₀ −P ₁ ) / (y ″ _(n−1) −b)] y ″ _(n−1) is calculated as the intercept A, and this is stored in the storage device 80.

Then, the flow shifts to step S414 to set the flag F1 to 1, and further shifts to step S415 to calculate the pressure command value P = K _GM · y ″ _(n) + A, and then shifts to step S407. This P is output as a pressure command value.If it is determined in step S411 that the flag F1 = 1, the process proceeds to step S416 to store the storage device 80.
_KGM and A stored in the memory are read, and step S
The process proceeds to 415 to calculate the pressure command value P = K _GM · y ″ _(n) + A, and then proceeds to step S407 to output this P as a pressure command value. After the output, the process returns to the main program of FIG.

Next, of the operation of this embodiment, only the control amount when the roll returns (a part different from the first embodiment) is shown in FIG.
It is shown below based on For the left wheel (outer wheel) at the time of turning right, when the roll returns, that is, when the lateral acceleration y ″ that is equal to or more than _ac decreases, until steps y ″ = b, steps S401 to S402, This state is determined in step S410 after step S409 and step S41.
Leads to 1, in step S412,413 (P ₀ -P ₁₎
/ (Y ″ _{(n −1)} −b) as K _GM (gain) and P ₀ −
_{[(P 0 -P 1) / (} y "(n-1) -b) ] y" _(n-1) was calculated as the intercept A, the following steps S411 S41
After passing through two points (b, P ₁ ) and (a, P ₀ ) at S 415 via S 414 to S 414 or S 416, a straight line L ₄ (an intercept is A and a slope K _GM ) is proportional to the lateral acceleration y ″. The control is performed so that the pressure command value P decreases.

When the lateral acceleration y ″ further decreases and y ″ ≦ b, this state is determined in step S410, and the process proceeds to step S404. P = K _G calculated in step S404 and set in steps S405 to 406. · y _"(n) the pressure command value P along a straight line L ₁ represented by is controlled so as to reduce. that is, the left wheel side hydraulic cylinder 18FL,
The working pressure p of 18RL is controlled to a lower pressure when y "> b than when the lateral acceleration is increased, and is controlled to be the same as when the lateral acceleration is increased when y" ≤b.

[0047] Thus, the energy E _a that is accumulated in the interposed a spring between the vehicle body and the left wheel "is released while the a b a a, y" y = vehicle the original when the b Return to posture. As for the pressure command value for the right wheel serving as the inner wheel, when the roll is returned, as shown in FIG.
There increases the pressure command value P along the straight line L ₄ and symmetric straight line L ₄₁ across the horizontal axis while the b from a, in the y "≦ b is controlled to return to L _1, right The operating pressure p of the wheel-side hydraulic cylinders 18FR and 18RR is controlled to a higher pressure when y "> b than when the lateral acceleration is increased, and the same as when the lateral acceleration is increased when y" ≤b. As a result, the roll slowly returns until y ″ = b while energy is supplied to the spring interposed between the vehicle body and the right wheel.

As described above, when the roll returns, the energy stored in the outer ring-side spring is released in accordance with the decrease in the lateral acceleration, and the energy is supplied to the inner ring-side spring in accordance with the decrease in the lateral acceleration. Since the pressure command value is corrected, the roll returns slowly over a longer time than in the conventional case, and the vehicle body can be returned to its original position without changing the roll center. By setting to, the sense of discomfort given to the occupant can be further reduced.

Here, the relationship between the lateral acceleration y ″ and the amount of released energy is compared with that of the first embodiment in FIG.
1 and 12 are shown by graphs. In FIG. 11 showing the first embodiment, since the amount of released energy is constant until the lateral acceleration becomes 0, the vehicle body is gradually moved by the energy released by the decrease in the lateral acceleration as shown by the solid line in FIG. When the vehicle is accelerated in the reverse roll direction and returns to straight running, this speed becomes the initial speed, and there is a case where roll rollback cannot be avoided. On the other hand, in the second embodiment, as shown in FIG.
Before the lateral acceleration becomes zero (| y ″ | = b), the energy is completely released before the roll acceleration becomes zero before returning to straight running as shown by the broken line in FIG. Therefore, it is difficult for the swingback to occur.

In this program, step S40
9 to 416 correspond to the spring degeneration correction means of the present invention. Here, even if is less than a _c lateral acceleration y "lateral acceleration y is in the reduced state", but K _GM and A is calculated in step S409～416, at this time K _GM =
K _G , A = 0, and the pressure command value P is decreased along the straight line L ₁ from the beginning. That is, steps S409 to S416 in this case do not correspond to the spring deformation correcting means of the present invention. In this case, however, it is necessary to correct the spring because the above-described energy (for example, Ea when y ″ = _a ) is not generated. Nor.

A third embodiment of the present invention will be described with reference to FIGS. FIG. 14 is a schematic configuration diagram of this embodiment. Vehicle height sensors 27a to 27d for the respective wheels are added to FIG. 2 showing the configuration of the first and second embodiments, and the vehicle height sensors 27a to 27d are added. The detection signals f _{FL to} f _RR from 27d are output to the controller 30a. As shown in FIG. 15, the detection signal f indicates that the stroke ST has a predetermined standard value ST _0.
At this time, f = f _N (predetermined standard stroke detection value).

As shown in FIG. 16, the controller 30a includes, in the controllers 30 of the first and second embodiments, A / A signals for detection signals f _{FL to} f _RR input from the vehicle height sensors 27a to 27d. D converters 70a to 70d are added. The microcomputer 72 stores the programs shown in FIGS. First, the detection signal g of the lateral acceleration sensor 26 is read in step S1 of the flowchart of FIG. 17, and the process proceeds to step S2. In this step S2, the neutral lateral G detection value g _N is subtracted from the detection signal g read in step S1, and
A lateral acceleration detection signal Δg is obtained. Next, the process proceeds to step S3, and the lateral acceleration y ″ corresponding to the detection signal Δg is calculated by referring to a storage table stored in the storage device 80 in advance.

Next, the process proceeds to step S4, where the detection signals f _{FL to} f _RR of the respective vehicle height sensors 27a to 27d are read, and the process proceeds to step S5. In step S5, the detection signal f _FL ~f _RR of the vehicle height sensors 27a~27d by subtracting the standard stroke detection value f _N, obtains the vehicle height detection signal Δf _FL ~Δf _RR for each wheel. Next, the process proceeds to step S6, and the strokes ST _{FL to} ST _RR corresponding to the detection signals Δf _{FL to} Δf _RR are calculated by referring to a storage table stored in the storage device 80 in advance.

Next, the flow shifts to step S7, in which the pressure command values P _{FL to} P _RR of each wheel are set according to a subroutine shown in FIG. The flag F1 in this program is F1
When = 1, it means that the lateral acceleration is decreasing during the turning convergence, and the operating pressure correction control is being performed. When F1 = 0, the lateral acceleration is increasing due to the turning and the operating pressure correction is being performed. Does not go.

That is, in step S71, the previous and current lateral accelerations y ″ _(n−1) , y ″ _{(n) and the} current stroke ST _(n) are read, and the flow advances to step S72.
Here, by comparing the previous lateral acceleration y ″ _(n−1) with the current lateral acceleration y ″ _(n) , it is determined whether the lateral acceleration is increasing or decreasing. If the lateral acceleration decreases (ie, | y ″ _(n) | − | y ″ _(n−1) | <0), the process proceeds to step S73 to determine whether the flag F1 = 1. If F1 ≠ 1, the process moves to step S74, and
Stroke ST _M at the time of maximum roll stroke ST a _(n)
After that, the process moves to step S75 and sets the flag F1 = 1.

[0056] If it is determined that the flag F1 = 1 at step S73, reads the standard stroke ST ₀ the process proceeds to step S76, ST and proceeds to step S77
_(n) = to determine whether the ST _0. If ST _(n) ≠ ST ₀ , the process proceeds to step S78 and the pressure correction value ΔP = K
It calculates the _{(ST M} -ST _(n)) the process proceeds to step S79. Here, K is a predetermined gain. The transition from reading normal pressure command value P _r in step S80 in step S79, and outputs the pressure command value P = P _r + [Delta] P. Here, the normal pressure command value _Pr is set so that the stroke ST linearly changes with respect to the lateral acceleration y ″ as shown in FIG. , For the inner wheel side, and is calculated by individual processing (not described in detail) and updated and recorded in the storage device 80.

[0057] ST in step S77 _(n) = ST ₀ and the determined case and step S72 in the lateral acceleration increases in a direction _{(i.e., | y "(n) |} - | y" (n-1) | ≧ 0 ), The process proceeds to step S81 and ΔP =
0, and proceeds as F1 = 0 in step S79, the process moves from reading the normal pressure command value P _r in step S80 outputs the pressure command value P = P _r + [Delta] P. That it is, outputs the normal pressure command value P _r as the pressure command value P. When the pressure command value P is output in step S80, as shown in FIG.
Return to the main program.

Thereafter, the arithmetic processing unit 78 proceeds to step S8 in FIG. 17, and the voltage command values V _{FL to} V _RR (set in step S7) for achieving the pressure command values P _{FL to} P _RR for each wheel. (The value corresponding to the actual operating pressure p obtained by adding the neutral pressure _PN to the pressure command values P _{FL to} P _RR ). Then, the process proceeds to step S9 to individually output the voltage command values V _{FL to} V _RR to the D / A converters 73A to 73D via the interface circuit 76.

Next, the operation of this embodiment will be described. | Y ″ _(n) | − |
Since y ″ _(n−1) | ≧ 0, steps S71 to S7
2, the process proceeds to S79 through S81, and in step S80, the normal pressure command value _Pr is output as the pressure command value. At this time, the operating pressure p of the hydraulic cylinders on the basis of the normal pressure command value P _r, increased for the outer ring with the increase of the lateral acceleration is controlled to decrease for the inner ring, thereby as shown in FIG. 19 In addition, as the lateral acceleration increases, a roll occurs in the vehicle body, so that the stroke on the inner wheel side increases and the stroke on the outer wheel side decreases.

Then, steps S71 to S72, S7
Roll On return leading to 3, until the stroke ST _(n) is the standard stroke ST _0, in step _{S74 | y "(n) |} - | y" (n-1) | moment became <0 Stroke ST _(n) is the maximum stroke ST
After being stored as _M , the state is determined in step S77 through steps S73 to S76, and the process proceeds to steps S78 to S80, where the absolute value of the lateral acceleration decreases and the stroke S
Control is performed so that the absolute value of the pressure correction value ΔP increases as the difference between T _(n) and the standard stroke ST ₀ decreases. When the stroke ST _(n) is returned to the standard stroke ST _0, reaches this state is determined in step S79 through step S81 in step S77, the set here under normal pressure command value P _r is the pressure command in step S80 Output as value P.

[0061] That is, the pressure correction value ΔP to be added to the normal pressure command value P _r is controlled in accordance with the stroke ST _(n) as shown in FIG. 20, a force for returning to the original deformation of the spring force against the (normal pressure command value P _r) (pressure correction value P) is given. Accordingly, the operating pressure of the outer wheel side hydraulic cylinder 18 is controlled to a lower pressure than when the lateral acceleration is increased, and the operating pressure of the inner wheel side hydraulic cylinder 18 is controlled to a higher pressure than when the lateral acceleration is increased. You. That is, the energy corresponding to the pressure correction value ΔP is released on the outer wheel side, and the energy corresponding to the pressure correction value ΔP is supplied to the inner wheel side, so that the roll returns slowly.

Thus, as shown in FIG. 21, the integral value of the vehicle body acceleration in the returning direction of the spring, that is, the roll speed in the reverse direction of the vehicle body, is changed to the convergence point of the roll acceleration, that is, from the turning to the straight traveling. Since it can be set to 0 or smaller at the time of transition, it is possible to prevent swinging back when going straight from turning. Further, since such control is performed on both sides of the outer wheel and the inner wheel, the vehicle body can be returned to the original position without changing the center of the roll. In this way, the uncomfortable feeling felt by the occupant when the roll returns can be reduced.

In the above embodiment, the lateral acceleration sensor 2
6, A / D converter 70, and steps S1 to S1 in FIG.
The processing in S3 constitutes the lateral acceleration detecting means, and the vehicle height sensor 2
17a to 27d, the A / D converters 70a to 70d, and the processing of steps S4 to S6 in FIG. 17 constitute a stroke detecting means. Steps S7 to S8 in FIG. 17 correspond to command value calculating means. Step S9, the D / A converters 73A to 73D, and the drive circuits 74A to 74D constitute command value output means. In this program,
Steps S73 to S80 correspond to the spring deformation correcting means of the present invention.

As described above, in each of the above-described embodiments, when the vehicle body rolls back, the pressure command value releases the energy stored in the outer ring side spring by the spring deformation correcting means at the time of rolling, and also transfers the energy to the inner ring side spring. Although the correction has been made so as to supply, the spring deformation correction means of the present invention may correct only one of the outer ring side and the inner ring side as described above.

The means for determining the lateral acceleration according to the present invention comprises:
Means for estimating the lateral acceleration based on, for example, the vehicle speed and the steering angle are not limited to those having a structure for directly detecting the inertial force using the lateral acceleration sensor as described above (for example, see Japanese Patent Application Laid-Open No. 62-293167). ). Also,
Naturally, the present invention can also be applied to an active suspension that also performs pitch control and bounce control of the vehicle body.

Further, the fluid cylinder of the present invention is not limited to the case where a hydraulic cylinder is applied as in the above embodiment, but may be, for example, a configuration using a pneumatic cylinder or the like. May be used to control the flow rate.

[0067]

As described above, in the active suspension according to the first aspect, when the vehicle body roll returns, the amount of deformation of the spring caused by the roll is corrected by the spring deformation correcting means. If the energy stored in the spring on the outer wheel is released or the energy is supplied to the spring on the inner wheel when turning, the roll returns slowly, and the occupant is required to recover when the roll of the vehicle body generated during turning is restored. Discomfort to the person.

According to the active suspension of the present invention, the correction is performed by releasing the energy stored in the spring on the turning outer wheel side at the time of rolling and supplying the energy to the spring on the turning inner wheel side. And the vehicle body can be returned without changing the center of the roll, so that the uncomfortable feeling given to the occupant when the rolled vehicle body returns the vehicle body can be further reduced.

According to the active suspension of the third aspect, when the energy of the turning outer wheel and the energy of the inner wheel are corrected, for example, the rate of decrease of the control pressure of the outer wheel and the rate of increase of the inner wheel with respect to the decrease of the lateral acceleration accompanying the turning convergence are corrected. By doing so, the roll returns slowly, and the uncomfortable feeling given to the occupant when the roll of the vehicle body is restored when the vehicle turns can be reduced.

According to the active suspension of the present invention, when the energy of the turning outer wheel and the energy of the inner wheel are corrected, the suspension stroke is detected, and when the roll returns, it is changed in a direction to suppress the stroke change rate. In addition, it is difficult for the roll to return when the roll returns, and it is possible to reduce the uncomfortable feeling given to the occupant when the roll of the vehicle body that occurs when turning is restored.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a schematic configuration diagram showing first and second embodiments of the present invention.

FIG. 3 is a graph showing output characteristics of a pressure control valve.

FIG. 4 is a graph showing detection characteristics of a lateral acceleration sensor.

FIG. 5 is a block diagram illustrating an example of the controller of FIG. 4;

FIG. 6 is a flowchart illustrating an example of a processing procedure executed in a controller according to the first and second embodiments.

FIG. 7 is a flowchart of a subroutine corresponding to step S4 of the flowchart of FIG. 6 according to the first embodiment.

FIG. 8 is a control characteristic diagram of a pressure command value in the first embodiment.

FIG. 9 is a flowchart of a subroutine corresponding to step S4 of the flowchart of FIG. 6 according to the second embodiment.

FIG. 10 is a control characteristic diagram of a pressure command value in the first embodiment.

FIG. 11 is a graph showing the relationship between the lateral acceleration y ″ when the roll returns and the amount of energy released in the first embodiment.

FIG. 12 is a graph showing the relationship between the lateral acceleration y ″ when the roll returns and the amount of energy released in the second embodiment.

FIG. 13 is a graph showing a relationship between a roll acceleration and a roll speed when the roll returns in the first and second embodiments.

FIG. 14 is a schematic configuration diagram showing a third embodiment of the present invention.

FIG. 15 is a graph showing detection characteristics of a vehicle height sensor.

FIG. 16 is a block diagram illustrating an example of the controller in FIG. 14;

FIG. 17 is a flowchart illustrating an example of a processing procedure executed in a controller according to the third embodiment.

FIG. 18 is a schematic flowchart of a subroutine corresponding to step S7 in the flowchart of FIG. 17 according to the third embodiment.

FIG. 19 is a graph showing a relationship between a lateral acceleration y ″ and a stroke ST in the third embodiment.

FIG. 20 is a graph showing a relationship between a pressure correction value ΔP and “stroke ST _(n) −standard stroke ST ₀ ” in the third embodiment.

FIG. 21 is a graph showing a relationship between a roll acceleration and a roll speed when the roll returns in the third embodiment.

FIG. 22 is a control characteristic diagram of a conventional operating pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Body member 12 Active suspension 14 Body member 18FL-18RR Front left to rear right hydraulic cylinder (fluid cylinder) 20FL-20RR Front left to rear right pressure control valve 26 Lateral acceleration sensor (lateral acceleration detecting means) 27a to 27d Vehicle height sensor (stroke detecting means) 36 Coil spring (spring) 70 A / D converter (lateral acceleration detecting means) 70a to 70d A / D converter (stroke detecting means) 73A to 73D A / D converter (command value) Output means) 74A to 74D Drive circuit (command value output means)

Claims (4)

(57) [Claims] 1. A fluid cylinder and a spring interposed for each wheel between a vehicle body-side member and a wheel-side member, a control valve for individually controlling each of the fluid cylinders according to a command value, A lateral acceleration detecting or estimating means for detecting or estimating the acceleration in the direction, and a command value calculation for calculating, for each wheel, a command value to be given to each control valve based on the lateral acceleration detection or estimating value of the lateral acceleration detecting or estimating means. Means, and a command value output means for respectively outputting the command value calculated by the command value calculation means to the control valve, wherein the command value calculation means comprises: An active suspension having spring deformation correcting means for correcting the amount of deformation of a spring with respect to the command value. 2. The active device according to claim 1, wherein said spring deformation correcting means discharges energy stored in a spring on a turning outer wheel when rolling the vehicle body and supplies energy to a spring on a turning inner wheel. Type suspension. 3. The active type according to claim 1, wherein said spring deformation correcting means corrects the amount of deformation of said spring in accordance with the lateral acceleration detected or estimated by said lateral acceleration detecting or estimating means. suspension. 4. The active suspension according to claim 1, wherein said spring deformation correcting means comprises a stroke detecting means, and corrects a deformation of said spring in accordance with a value detected by said stroke detecting means. .